Our Large Soil Box, which has a 270 ml (270 cm³) volume is compatible with 4-Terminal Resistance Meters such as the Miller 400A, the Miller 400D and the Nilsson 400 Resistance Meters.

Miller Soil Boxes can be used to satisfy either the 4-electrode method (ASTM G57 Standard) or the 2-electrode methods (ASTM G187 or AASHTO T-288 Standards).

For the 2-electrode method, the two interior pins are removed which changes the multiplication factor from 1cm (for the 4-electrode method) to either 0.67 cm for the small box or to 0.57 cm for the large box. Please see the following link for details: ASTM G57 and AASHTO T-288 Standard Methodologies.

• Plexiglas body with rounded corners for easy cleaning
• Stainless steel current distribution plates and removable brass pins (potential measurement pins)

Critical Dimensions (for 4-electrode method, i.e. the two interior pins are in use): The soil boxes are designed such that the cross-sectional area of the soil (or liquid) sample (A), with the box filled level, divided by the separation between the pins (L) is equal to 1 cm.

• Cross-sectional area = 4 cm x 3.2 cm = 12.8 cm²
• Pin separation = 12.8cm
• A / L = 1 cm

Soil Box Example: M.C.Miller Factory Tap Water

Measured Resistance	= 1.97 kΩ
Resistivity Value	= 1.97 kΩ x 1 cm
	= 1,970 Ω.cm
[Hence, MCM Water Conductivity = 507 µS/cm]